Incidental Nodal Lymphangioleiomyomatosis Is Not a Harbinger of Pulmonary Lymphangioleiomyomatosis: A Study of 19 Cases With Evaluation of Diagnostic Immunohistochemistry.

Lymphangioleiomyomatosis (LAM) is a proliferation of perivascular epithelioid cells typically affecting the lung as a low-grade, destructive and progressive disease but may also be found in lymph nodes and other organs. LAM is sometimes seen as an incidental finding in lymph node dissections performed for staging of gynecologic tumors. To our knowledge, no study has investigated the clinical significance of incidental nodal LAM in relation to subsequent development of pulmonary LAM. We identified 19 patients from our institution with LAM in lymph nodes. Follow-up was available for 100% of patients and ranged from 3 to 123 months (mean 33.8 mo). All were women, ranging in age from 35 to 71 years (mean 56.3 y). None had a history of tuberous sclerosis, renal angiomyolipoma, or pulmonary LAM. LAM involvement spanned 1 to 6 nodes (mean 2), ranging from 1% to 100% of the total excised lymph nodes. The single largest focus of nodal LAM ranged from 1 to 9 mm (mean 4.3 mm) in 18 patients without evidence of persistent or recurrent nodal LAM. In the 1 patient with persistent local nodal LAM, the greatest diameter was 25 mm. Affected lymph node sites were regional pelvic and retroperitoneal chains routinely sampled in staging operations. An immunohistochemical panel of HMB45, A103, and β-catenin was evaluated in 18 cases. HMB45 showed strong but usually focal staining in every case compared with A103, which was very focally expressed (39%) or negative. β-catenin showed strong, diffuse cytoplasmic and membranous (non-nuclear) reactivity in 100% of cases. At the last clinic visit, all 19 patients had no manifestations of pulmonary LAM. In an absence of signs of symptoms of extranodal LAM, patients with incidentally discovered nodal LAM smaller than 10 mm are not at risk of developing pulmonary LAM.